During rescue operations, particularly at sea, it is often useful to throw a line to a person to assist in rescuing the person. While it is possible to simply throw a line to someone who is close, it can be a problem to throw a line to someone who is more than about 15 meters away. In sea rescue situations it is common to not be able to get any closer than about 20 to 40 meters to a person in difficulty.
For this reason a number of line launchers have been produced. These are devices that have been designed to launch a projectile which will drag out a line behind it. Some devices use self propelled projectiles.
However the presently available line launchers are often quite complex and/or expensive to use. Some use pyrotechnic devices and can require special licensing to own and use. The initial cost, the complexity, the specialised training requirements, the specialised storage requirements, the maintenance requirements, and/or the cost of use, has meant that these devices are often not carried on rescue vehicles.